Typomorphic Features and Source of Native Gold from the Sykhoi Log Area Placer Deposits, Bodaibo Gold-Bearing District, Siberia, Russia

Round 1

Reviewer 1 Report

Dear authors,

I think that your contribution is of interest to a broad audience interested in placer gold. The analysis and results obtained from your work are very interesting.

I am attaching a few comments.

Comments for author File: Comments.pdf

Author Response

Thank you so much for the review. All your comments and suggestions were taken into account in the new version of the article.

Author Response File: Author Response.pdf

Reviewer 2 Report

Please use the attached annotated pdf for your revision as much as you can.

Lines 2-4: Title can be improved as follows: “Typomorphic features and source of native gold from the Sykhoi Log area placer deposits, Bodaibo gold-bearing district, Siberia, Russia”.

Instead of: “Typomorphic features of native gold of Sykhoi Log area (Bodaibo gold-bearing district, Siberia) and sources of gold placer deposits”.

Abstract is ok but it needs some modifications as indicated in the attached annotated pdf. Keywords are enough and ok too.

Lines 11 and 13: Talking about Au-Ag alloys is contradiction for what you already mentioned in line 11. Native is native and no need to mix with the electrum mixture, i.e. the Au-Ag alloy. Please be precise and determinative.

Line 49: You need to inert geographic north here (N) and an arrow parallel to the longitudes.

Line 60: Plural of evidence is the same as its singular form, which is the same case of information for example.

Line 111, Fig. 2: Geographic north is missing here. Please insert (N). Degree is missing for the 116 East longitude. Also, it is preferable to add E and N for the digits of each latitude and longitude.

Line 124: A very critical issue is the unification of the use of either "sulphides" or "sulfides" here and all over the text.

Lines 133-135, Fig. 3: You need to show a scale for this geological map. Also, on what basis you draw the width and length of gold placer deposits (red) as a part of the Quaternary alluvium?. Does it rely on speculations depending on the field, or you have geochemical haloes or any kind of remotely-sensed data?.

Line 141: It is better if you can use fine stockwork and dissemination instead.

Lines 147-148: You have a font problem here so you need to re-edit.

Lines 179-180: Do you have a reference to support this age assignment (Miocene)?. Are there any stratigraphic information of your own?.

Line 228: What kind of heavy liquids did you use to extract heavy mineral concentrates from your stream sediments?. For example bromoform or clercil solution and please give the liquid density in g/cm3.

Line 230: You firstly mention about scanning electron microscopy here so you need to write it in full plus SEM between brackets same as you did for the EMPA.

Line 248: For the analytical procedures section, In Table 1, you give good information about the operating conditions and distribution of metals among the spectrometers. Nevertheless, you need to mention standards used to calibrate the electron microprobe, and state clearly if they are natural or synthetic minerals/alloys.

Line 282, Fig. 5: I guess you mean binocular when you say "optical", isn't it?. This is the most convenient tool to investigate mineral grain morphology microscopically.

Line 296: Are they Fe oxides only?. What about common Fe-hydroxides and Fe-oxyhydroxides in placer gold?.

Lines 324-325, Fig. 6: I doubt it is sphalerite?!!!. They are polishing pits most probably. Also, galena looks strange and of odd bluish to violet tint. In polished mounts, galena is white owing to its high reflectivity.

Line 370, Fig. 8: You report only two types in your legend for Fig. 8. It is a must to report the rest, and better if you can skip legend here and mention in the captions that are gold types are as in Figure 7.

Line 386, Fig. 10: Why does pyrite appear dark in the BSE image in Fig. 10c?.

Line 404: Use Mineral inclusions instead of inclusion suites.

Line 414: Problem of font appears again here. Also in lines 422 and 423.

Lines 560 to 586: You rely on previous work more than you do for your own field observations supported by the analytical data. You need to rephrase this important part of your discussion section.

Lines from 605-610 in the discussion section too: Enough information about the source rocks and issue of provenance is lacking here or at least vague.

Line 647: The reference list is ok but more care must be paid for punctuation particularly when it comes to abbreviations of journal name.

Comments for author File: Comments.pdf

The MS needs moderate polishing.

Author Response

I want to express my deep gratitude to the reviewer for the great work done, which allowed us to eliminate a number of errors and significantly improve the quality of the article. In general, all comments were accepted by us, the corresponding corrections were made to the article. A few points that we would like to explain are set out in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

An excellent paper but it requires careful editing of the English.

Comments for author File: Comments.pdf

Author Response

Thank you very much for the review. Thanks to your proofreading, the English of our article has improved significantly.

Round 2

Reviewer 2 Report

Thank you for the correction you made to improve the quality of your research before publication.

It is acceptable and just needs fine English polishing.